They call it "merchant usage patterns," and, believe it or not, credit card companies can look to see where you're swiping your plastic to determine how risky of a borrower you are.

According to John Ulzheimer, a disproportionate use of your credit card at bars and pubs can be seen as risky - but he stresses the word 'disproportionate.' Don't be afraid to buy a round for your friends next Happy Hour, just be careful to avoid racking up too many bar tabs and not much else.

The other big one? Marriage counseling. Credit card issuers know that divorce trashes most people's credit, and counseling is a predictor - in their eyes, at least - of a potential divorce.

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